CN108565870B - Method for evaluating static voltage stability of power grid system based on PSSE - Google Patents

Abstract

The invention discloses a method for evaluating static voltage stability of a power grid system based on PSSE (power system optimization), which comprises the following steps: accessing a virtual load in an evaluation node of a power grid system; setting the active power and the reactive power of the virtual load; setting a control mode of an SVC model in PSSE, and setting control parameters of an active power, a reactive power, a voltage control module and a reactive group in the SVC model so that the SVC model simulates the MSC/MSR function; accessing the SVC model to the evaluation node to form a first simulation scene; disconnecting the SVC model at the evaluation node to form a second simulation scene; and performing PV and QV analysis on the first simulated scene and the second simulated scene. The PSSE static voltage stability analysis method can effectively utilize the SVC model of the PSSE to replace MSR/MSC control characteristics to analyze the static voltage stability of the needed power grid node, and is beneficial to the MSR/MSC functional verification and the influence analysis research on the static voltage stability in the early stage of STATCOM access engineering.

Description

Method for evaluating static voltage stability of power grid system based on PSSE

Technical Field

The invention relates to the field of simulation systems, in particular to a method for evaluating the stability of static voltage of a power grid system based on PSSE.

Background

The stability of the power system is always the focus of global attention, and since the 60 th century, the case of system instability caused by voltage instability occurs in foreign power grids for many times. The principle of voltage stability is relatively complex, and in order to prevent voltage instability and voltage collapse accidents, a dispatcher usually most cares about the indexes that whether the system running state is voltage stability or not, the domain degree from the voltage instability and the like are about large. Many developed countries have developed software for analyzing voltage stability, such as PSSE. With the development of technologies such as dynamic reactive power compensation equipment and the like, the dynamic reactive power supporting capability of the voltage weak node is improved, and the stability is greatly improved.

At present, in some general packet projects of international STATCOM equipment, a user needs a constructor to provide analysis content of influence of an MSR (Mechanical Switch Reactor)/MSC (Mechanical Switch capacitor) on static voltage stability of an access node in system research. However, the existing international power system analysis software PSSE does not contain the model of MSR/MSC, so that the PSSE software cannot be directly used for analysis, and the analysis of the stability influence of MSR/MSC on the node static voltage cannot be provided.

Disclosure of Invention

The embodiment of the invention aims to provide a method for evaluating the stability of static voltage of a power grid system based on PSSE (Power System State optimization), which can effectively utilize an SVC (static var compensator) model carried by PSSE to replace MSR/MSC (modeling support vector machine/mobile switching center) control characteristics to analyze the stability of the static voltage of a required power grid node, and is beneficial to carrying out MSR/MSC functional verification and analysis and research on the influence of MSR/MSC on the stability of the static voltage in the early stage of STATCOM access engineering.

In order to achieve the above object, an embodiment of the present invention provides a method for evaluating static voltage stability of a power grid system based on PSSE, including:

accessing a virtual load in an evaluation node of a power grid system;

setting the active power and the reactive power of the virtual load;

setting a control mode of an SVC model in PSSE, and setting control parameters of an active power, a reactive power, a voltage control module and a reactive group in the SVC model so that the SVC model simulates the MSC/MSR function;

accessing the SVC model to the evaluation node to form a first simulation scene;

disconnecting the SVC model at the evaluation node to form a second simulation scene;

and performing PV and QV analysis on the first simulated scene and the second simulated scene.

Compared with the prior art, the method for evaluating the static voltage stability of the power grid system based on the PSSE selects an evaluation node in the actual power grid system, sets the virtual load in the evaluation node, simultaneously accesses the SVC model in the PSSE to the evaluation node, and then interrupts the SVC model at the evaluation node to form a second simulation scene; and finally performing PV and QV analysis on the first simulated scene and the second simulated scene. The problem that in the prior art, a PSSE (power system integration standard) does not contain a model of MSR/MSC (modeling system/mobile switching center), so that analysis cannot be directly performed through PSSE software, and therefore analysis of the influence of MSR/MSC on the stability of the static voltage of the node cannot be provided is solved, the SVC model carried by the PSSE can be effectively used for replacing the MSR/MSC control characteristic to perform the stability analysis of the static voltage of the required power grid node, and the MSR/MSC function verification and the influence analysis research on the stability of the static voltage at the early stage of STATCOM access engineering are facilitated.

As an improvement of the scheme, the active power is set to be 1MW, and the reactive power is set to be 0 MW.

As a modification of the above, the control mode is discrete voltage control; the highest voltage in the voltage control module is 1.05p.u., and the lowest voltage in the voltage control module is 0.95p.u.

As an improvement of the above scheme, in the reactive groups, both the first reactive group and the second reactive group are 1, and the rest reactive groups are set to be 0;

the reactive power switching rates of the first reactive power group, the second reactive power group and the rest of the reactive power groups are 100%, and the initial reactive power switching value is 0.

As an improvement of the above scheme, the MSR switching capacity of the first reactive group corresponding to the action voltage is-250 Mvar, and the MSC switching capacity of the second reactive group corresponding to the action voltage is 125 Mvar.

As an improvement of the above scheme, the performing PV and QV analysis on the first simulated scene and the second simulated scene specifically includes:

and selecting the evaluation node as a power inflow node, selecting all nodes except the evaluation node as power outflow nodes, selecting three system faults to respectively simulate three-phase short-circuit faults, and respectively carrying out PV and QV analysis on the first simulation scene and the second simulation scene based on the evaluation node.

Drawings

Fig. 1 is a flowchart of a method for evaluating static voltage stability of a power grid system based on PSSE according to an embodiment of the present invention;

fig. 2 is a schematic diagram of an evaluation node in a method for evaluating static voltage stability of a power grid system based on PSSE according to an embodiment of the present invention;

fig. 3 is a graph of PV evaluation results of a first simulation scenario in a method for evaluating static voltage stability of a power grid system based on PSSE according to an embodiment of the present invention;

fig. 4 is a graph of PV evaluation results of a second simulation scenario in the method for evaluating static voltage stability of a power grid system based on PSSE according to the embodiment of the present invention;

fig. 5 is a graph of a QV estimation result of a first simulation scenario in the method for estimating the stability of the static voltage of the power grid system based on the PSSE according to the embodiment of the present invention;

fig. 6 is a graph of a QV estimation result of a second simulation scenario in the method for estimating the stability of the static voltage of the power grid system based on the PSSE according to the embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a flowchart of a method for evaluating static voltage stability of a power grid system based on PSSE according to an embodiment of the present invention; the method comprises the following steps:

s1, accessing a virtual load in an evaluation node of the power grid system;

s2, setting the active power and the reactive power of the virtual load;

s3, setting a control mode of an SVC model in the PSSE, and setting control parameters of an active power module, a reactive power module, a voltage control module and a reactive power group in the SVC model so that the SVC model simulates the MSC/MSR function;

s4, accessing the SVC model to the evaluation node to form a first simulation scene;

s5, disconnecting the SVC model at the evaluation node to form a second simulation scene;

and S6, performing PV and QV analysis on the first simulated scene and the second simulated scene.

Specifically, in step S1, referring to fig. 2, fig. 2 is a schematic diagram of an evaluation node in the method for evaluating static voltage stability of a power grid system based on PSSE according to the embodiment of the present invention, where a power grid system includes a plurality of nodes, such as nodes 1 to 12 in fig. 2, where node 11 is the evaluation node; preferably, the grid system further comprises at least one load, such as load a1, load a2, load A3 and load a4 shown in fig. 2, wherein the load a4 is a load connected to the evaluation node 11; preferably, the grid system further includes at least one transformer, such as a transformer N1, a transformer N2, a transformer N3, a transformer N4 and a transformer N5 shown in fig. 2, wherein two ends of the transformer N5 are connected to the evaluation node 11 and the node 12, respectively; preferably, the power grid system further comprises a generator G, and the nodes are connected through a power transmission line.

Specifically, in step S2, the active power and the reactive power of the virtual load are set; wherein the active power is set to 1MW and the reactive power is set to 0 MW.

Specifically, in step S3, a control mode of the SVC model in the PSSE is set, and control parameters of an active power, a reactive power, a voltage control module, and a reactive group in the SVC model are set, so that the SVC model simulates an MSC/MSR function; preferably, the control mode of the SVC model is set to discrete voltage control; setting the highest voltage to be 1.05p.u. and the lowest voltage to be 0.95p.u. in a voltage control module of the SVC model; setting a first reactive group (Block 1Steps) and a second reactive group (Block 2Steps) in the SVC model to be 1, and setting the rest reactive groups to be 0; setting the reactive switching rates (connected Vars) of the first reactive group, the second reactive group and the rest of the reactive groups to be 100% and setting an initial reactive switching value (Binit) to be 0; the MSR switching capacity of the action voltage corresponding to the first reactive power group is-250 Mvar, and the MSC switching capacity of the action voltage corresponding to the second reactive power group is 125 Mvar.

Specifically, in step S4, the SVC model (i.e., SW in fig. 2) is connected to the evaluation node 11, so as to form a first simulation scenario. At this point, the SVC model can be utilized to simulate the MSR/MSC effects on access node static voltage stability. In the prior art, a node in a power grid is accessed by using an MSR/MSC (multi-service mobile radio/mobile switching center) generally, so that the influence of the MSR/MSC on the static voltage stability of the access node is detected, and therefore, the influence of the MSR/MSC on the static voltage stability of the access node can be simulated by researching the influence of an SVC (static var compensator) model on the static voltage stability of the access node. The SVC (static var compensator) model is a specific PSSE model, and has the remarkable characteristic that the SVC model can be adjusted or switched frequently by depending on power electronic devices such as thyristors and the like to complete the adjusting or switching function. The SVC model is a fast-adjusting reactive power supply, and can adjust the system voltage and improve the transmission power of a line. It absorbs or transmits continuously adjustable reactive power from or to the power grid of the power system to maintain the voltage stability of the installation point and to facilitate the reactive power balance of the power grid.

Specifically, in step S5, the SVC model is disconnected at the evaluation node to form a second simulation scenario, where it is indicated that the power grid system does not include an MSR/MSC, and the second simulation scenario is used for comparing with the first simulation scenario and evaluating an influence on the system after the MSR/MSC is connected.

Specifically, in step S6, a three-phase short-circuit fault generally occurs in the existing grid system, and therefore, simulating the three-phase short-circuit fault in the grid system can better reflect the real grid condition. Specifically, the evaluation node 11 is selected as a power inflow node, all nodes except the evaluation node 11 are power outflow nodes, and three system faults are selected to respectively simulate a three-phase short-circuit fault, including a first system fault Case 1, a second system fault Case 2, and a third system fault Case 3.

And performing PV analysis and QV analysis on the first simulated scene and the second simulated scene respectively based on the evaluation node 11. The PV analysis refers to observing the active power transmission domain when the voltage is running under different scene conditions (when the power system normally runs, the reactive power output of the power supply is balanced with the reactive power consumption of the load and the network reactive power loss, if the power supply or the reactive power compensation capacity is in shortage, the voltage at the load is forced to be reduced, and when the voltage is reduced to a certain critical value, the voltage value is continuously reduced and cannot be recovered, namely, the voltage is collapsed); the QV analysis refers to the reactive power exchange domain degree when the voltage rushes to collapse under different scene conditions.

Specifically, referring to table 1, assuming that a regional power grid has 400 nodes with voltage levels of 132kV, 220kV, 400kV and 765kV, the PV analysis results in the first simulation scenario and the second simulation scenario are shown in table 1. The graph of the PV evaluation result of the first simulated scene is shown in fig. 3, and the graph of the PV evaluation result of the second simulated scene is shown in fig. 4.

In conjunction with table 1, fig. 3 and fig. 4, the PV evaluation result graph of the second simulation scenario (without MSR/MSC) in fig. 4 compares with the PV evaluation result graph of the first simulation scenario (with MSR/MSC) in fig. 3, and the active power of the first system fault Case 1, the second system fault Case 2 and the third system fault Case 3 in fig. 3 is respectively greater than the active power of the first system fault Case 1, the second system fault Case 2 and the third system fault Case 3 in fig. 4 under the condition of equal voltage, so that the active power transmission domain is increased after the MSR/MSC is connected.

TABLE 1 PV evaluation results

Specifically, referring to table 2, it is assumed that a power grid in a certain area has 400 nodes with voltage levels of 132kV, 220kV, 400kV and 765kV, and at this time, the QV analysis results in the first simulation scenario and the second simulation scenario are shown in table 2. The graph of the QV evaluation result of the first simulation scenario is shown in fig. 5, and the graph of the QV evaluation result of the second simulation scenario is shown in fig. 6.

In combination with table 2, fig. 5 and fig. 6, compared with the PV evaluation result graph of the first simulation scenario (including MSR/MSC) in fig. 3, the QV evaluation result graph of the second simulation scenario (without MSR/MSC) in fig. 5 has a larger reactive power of the first system fault Case 1, the second system fault Case 2 and the third system fault Case 3 in fig. 5 than the reactive power of the first system fault Case 1, the second system fault Case 2 and the third system fault Case 3 in fig. 6 respectively under the condition of equal voltage, so that the reactive switching domain is increased after the MSR/MSC is connected, and in conclusion, the SVC model in the present invention can effectively simulate the MSR/MSC action, and the evaluation method can reflect the influence of the MSR/MSC on the static voltage stability.

TABLE 2 QV evaluation results

As can be seen from fig. 3 to 6, by comparing the two cases of the switched-in SVC model (MSR/MSC) and the switched-out SVC model (MSR/MSC), it can be found that the SVC model (MSR/MSC) can correctly operate at the highest voltage (1.05p.u.) and the lowest voltage (0.95p.u.), that is, the SVC model has a certain influence on the stability of the voltage (the curve fluctuates).

Compared with the prior art, the method for evaluating the static voltage stability of the power grid system based on the PSSE selects an evaluation node in the actual power grid system, sets the virtual load in the evaluation node, simultaneously accesses the SVC model in the PSSE to the evaluation node, and then disconnects the SVC model from the evaluation node, thereby forming a first simulation scene; simultaneously acquiring a second simulation scene in which the evaluation node is not accessed to the SVC model; and finally performing PV and QV analysis on the first simulated scene and the second simulated scene. The problem that in the prior art, a PSSE (power system integration standard) does not contain a model of MSR/MSC (modeling system/mobile switching center), so that analysis cannot be directly performed through PSSE software, and therefore analysis of the influence of MSR/MSC on the stability of the static voltage of the node cannot be provided is solved, the SVC model carried by the PSSE can be effectively used for replacing the MSR/MSC control characteristic to perform the stability analysis of the static voltage of the required power grid node, and the MSR/MSC function verification and the influence analysis research on the stability of the static voltage at the early stage of STATCOM access engineering are facilitated.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (6)

1. A method for evaluating static voltage stability of a power grid system based on PSSE is characterized by comprising the following steps:

accessing a virtual load in an evaluation node of a power grid system;

setting the active power and the reactive power of the virtual load;

setting a control mode of an SVC model in PSSE, and setting control parameters of an active power, a reactive power, a voltage control module and a reactive group in the SVC model so that the SVC model simulates the MSC/MSR function;

accessing the SVC model to the evaluation node to form a first simulation scene;

disconnecting the SVC model at the evaluation node to form a second simulation scene;

performing PV and QV analysis on the first simulation scene and the second simulation scene; the PV analysis refers to the active power transmission domain degree when the voltage rushes under different scene conditions is observed; the QV analysis refers to the reactive power exchange domain degree when the voltage rushes to collapse under different scene conditions.

2. The PSSE-based method for assessing grid system static voltage stability of claim 1, wherein the active power is set to 1MW and the reactive power is set to 0 MW.

3. The PSSE-based method for assessing grid system static voltage stability of claim 1, wherein the control mode is discrete voltage control; the highest voltage in the voltage control module is 1.05p.u., and the lowest voltage in the voltage control module is 0.95p.u.

4. The PSSE-based method for assessing grid system static voltage stability of claim 3, wherein the first reactive subgroup and the second reactive subgroup of the reactive subgroups are both 1, and the remaining reactive subgroups are set to 0;

the reactive power switching rates of the first reactive power group, the second reactive power group and the rest of the reactive power groups are 100%, and the initial reactive power switching value is 0.

5. The PSSE-based method for evaluating the stability of the static voltage of the power grid system as recited in claim 4, wherein the MSR switching capacity of the first reactive power sub-group corresponding to the action voltage is-250 Mvar, and the MSC switching capacity of the second reactive power sub-group corresponding to the action voltage is 125 Mvar.

6. The PSSE-based method for evaluating grid system static voltage stability of claim 1, wherein the performing PV and QV analysis on the first and second simulated scenarios specifically comprises:

and selecting the evaluation node as a power inflow node, selecting all nodes except the evaluation node as power outflow nodes, selecting three system faults to respectively simulate three-phase short-circuit faults, and respectively carrying out PV and QV analysis on the first simulation scene and the second simulation scene based on the evaluation node.

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